Fan guard structure for additional supercharging function

ABSTRACT

A fan guard has a function of supercharging a fan in addition to supporting a rotor device is disclosed. The fan guard is to be mounted beside the rotor device for supporting the rotor device, and additionally, the fan guard interacts with an airflow generated by the revolution of the rotor blades to supercharge the fan. The fan guard essentially includes a main frame, and a set of guard blades radially arranged inside the main frame and fixed onto an inner surface of the main frame by each one end thereof. Each of the guard blades is preferred to have a shape similar to the shape of the rotor blades, and the set of guard blades can be arranged either upstream or downstream of the rotor blades.

FIELD OF THE INVENTION

The present invention is related to a fan guard structure, and moreparticular to an improved fan guard structure which imparts asupercharging function to a fan for efficient heat dissipation.

BACKGROUND OF THE INVENTION

Currently, heat-dissipating fans commonly used in personal computersinclude an axial-flow fan, a centrifugal fan and a cross-flow fan. Ofthese, the most popular one is supposed to be an axial-flow fan.

A fan is primarily consisted of a rotor device and a fan guard arrangedbeside the rotor device for supporting the rotor device. Referring toFIG. 1, the fan guard 10 of a conventional axial-flow fan is constructedby a main frame 101, a motor holder 102 and a plurality of ribs 103arranged between the main frame 101 and the motor holder 102. The rotordevice 11 includes a motor (not shown) received in the motor holder 102,a shaft ring 111 connected to and driven by the motor to revolve, and aplurality of rotor blades 112 fixed on the circumferential surface ofthe shaft ring 111 and revolving with the shaft ring 111 to work on thesurrounding air to generate an airflow. Through the work of the rotorblades on the surrounding air, the blast pressure is changed from arelatively low value on the air inlet side into a relatively high valueon the air outlet side. That is, there is a blast pressure enhancementon the air outlet side.

Unfortunately, when the airflow further flows through the fan guardhaving the structure as shown in FIG. 1 and as described above,turbulent flows will be generated after the airflow encounters the ribsso as to have an adverse effect on the blast pressure enhancement.Consequently, the efficiency of the fan is reduced.

SUMMARY OF THE INVENTION

Therefore, an object of the present invention is to provide an improvedfan guard structure which has a function of supercharging a fan inaddition to supporting a rotor device.

The present invention is related to a fan guard to be mounted beside arotor device of a fan for supporting the rotor device. Additionally, thefan guard according to the present invention interacts with an airflowgenerated by the revolution of the rotor blades to supercharge the fan.

The fan guard essentially includes a main frame, and a set of guardblades radially arranged inside the main frame and fixed onto an innersurface of the main frame by each one end thereof. Generally but notdefinitely, a count of the guard blades is about 1-2 times of that ofthe rotor blades. Preferably, the other ends of the guard blades arefixed onto a cylindrical motor holder which is located at the center ofthe main frame, and is hollow for receiving therein a motor used fordriving the rotor blades to revolve. Especially preferred, at least onereinforcing ring connecting all of the guard blades is provided forstrengthening the far guard. In general, the guard blades are made ofplastic. Nevertheless, the guard blades can also be made of a materialother than plastic for a desired purpose. For example, they can be madeof a metal which is advantageous for heat dissipation.

To assemble the fan, the main frame of the fan guard is coupled to theframe of the rotor device. Alternatively, the main frame of the fanguard is integrally formed with the frame of the rotor device so thatthe fan can be assembled by installing the non-integrally formed partsinto the common frame. The fan guard can be arranged either upstream ordownstream of the rotor device. Preferably, the fan guard includes twosets of frame and guard blades respectively arranged by both sides ofthe rotor device. By properly designing the shapes and the positionarrangement of the guard blades relative to the rotor blades, theupstream guard blades can guide air into the rotor device at an angle tomake an air inflow to the rotor device have an additional tangentialvelocity which increases the work of the rotor blades on air, and on theother hand, the downstream guard blades can transform a tangentialvelocity of an air outflow from the rotor device into a static pressure,both advantageous for supercharging the fan. For example, all of theguard blades are made to have a shape identical to the shape of therotor blades. As for the position arrangement of the downstream guardblades relative to the upstream rotor blades, one of the guard bladesand one of the rotor blades constitute a near letter C configuration ina cross-sectional view instantaneously. Contrarily, the positionarrangement of the upstream guard blades relative to the downstreamrotor blades makes one of the guard blades and one of the rotor bladesconstitute a near letter S configuration in a cross-sectional viewinstantaneously.

Furthermore, by taking the combination of a fan guard according to thepresent invention and a rotor device as a fan unit, a fan can bedesigned to include a plurality of such fan units to enhance efficiency.

BRIEF DESCRIPTION OF THE DRAWING

The present invention may best be understood through the followingdescription with reference to the accompanying drawings, in which:

FIG. 1 is a schematic diagram showing a conventional axial flow fan;

FIG. 2A is a resolving diagram of a first preferred embodiment of a fanaccording to the present invention;

FIG. 2B is a perspective diagram of the assembled fan of FIG. 2A withthe rotor device facing forwards;

FIG. 2C is a bottom view of the fan shown in FIG. 2B;

FIG. 2D is a bottom view of the fan guard shown in FIG. 2A;

FIG. 3 is a cross-sectional view of a rotor blade and a guard blade ofthe fan of FIG. 2;

FIG. 4 is a cross-sectional view of a rotor blade and a guard blade of asecond preferred embodiment of a fan according to the present invention;

FIG. 5A is a resolving diagram of a third preferred embodiment of a fanaccording to the present invention;

FIG. 5B is a cross-sectional view of a rotor blade and a guard blade ofthe fan of FIG. 5A;

FIG. 6 is a cross-sectional view of a rotor blade and a guard blade of afourth preferred embodiment of a fan according to the present invention;

FIG. 7 is a partially resolving diagram of a fifth preferred embodimentof a fan according to the present invention; and

FIG. 8 is a perspective diagram of a sixth preferred embodiment of a fanaccording to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention will now be described more specifically withreference to the following embodiments. It is to be noted that thefollowing descriptions of preferred embodiments of this invention arepresented herein for purpose of illustration and description only; it isnot intended to be exhaustive or to be limited to the precise formdisclosed. On the other hand, all arrows shown in the drawings are usedfor schematically illustrating the directions of airflows andvelocities, and the length of the arrows does not indicate the measureof the corresponding items.

Please refer to FIG. 2A FIGS. 2A and 2D which schematically shows arotor device and a preferred embodiment of a fan guard according to thepresent invention. The rotor device 21, as conventionally used, includesa motor 211, a shaft ring 212 connected to the motor 211, and aplurality of rotor blades 213 fixed on the circumferential surface ofthe shaft ring 212. The fan guard 20 includes a main frame 201, a motorholder 202, and a plurality of guard blades 203. The motor holder 202 isa hollow cylinder located at the center inside the frame for receivingtherein the motor 211. The guard blades 203 are radially disposed withinthe main frame 201. One end 2031 of each of the guard blades 203 isfixed onto the inner surface 2011 of the main frame 201 and the otherend 2032 thereof is fixed onto the circumferential surface 2021 of themotor holder 202. In this embodiment, the frames of the fan guard andthe rotor device are integrally formed as the main frame 201. In otherwords, the motor 211, shaft ring 212, rotor blades 213, motor holder202, and guard blades 203 are all positioned inside the main frame 201.

The assembled fan is shown on FIG. 2B FIGS. 2B and 2C. In thisembodiment, the rotor blades are located upstream of the guard blades.When the fan operates, the motor 211 (see FIG. 2A) drives the shaft ring212 with the rotor blades 213 to revolve. The revolution of the rotorblades 213 results in work on the surrounding air to generate anairflow. The arrows Fi and Fo in the figure indicates the air inflow andthe air outflow, respectively. Through the work of the rotor blades onthe surrounding air, the blast pressure is changed from a relatively lowvalue on the air inlet (Fi) side into a relatively high value on the airoutlet (Fm, FIG. 3) side. That is, there is a blast pressure enhancementon the air outlet (Fm) side. According to the present invention, theblast pressure can be further increased on the air outflow (Fo) sidethrough the guard blades of the fan guard for the reason described asfollows.

Please refer to FIG. 3. In order to concretely illustrate thearrangement of the guard blades, an upstream rotor blade 313 which canbe any one of the rotor blades and a downstream guard blade 303 whichcan be any one of the guard blades, are shown in a cross-sectional view,and a specific moment that a leading point A of the guard blade 303 ismoved to be axially aligned with the trailing point B of the rotor blade313 is taken to facilitate to describe the position relationship betweenthe selected rotor blade and guard blade. As shown, the rotor and theguard blades 313 and 303 constitute a near letter C configuration.

When the rotor device operates to have the rotor blade 313 revolve at atangential velocity Vr, the airflow arriving at the guard blade 303 hasan axial velocity and a tangential velocity. Due to conservation ofmass, the axial velocity will not change through the entire guard blade303, and is represented by a reference symbol Va in FIG. 3. Thetangential velocity, however, varies from a relatively high value Vtapproximating the velocity Vr of the rotor blade to a relatively lowvalue Vt′ down to zero. According to the Bernoulli's Law, the pressurewill increase with the decrease of velocity. The tangential velocity ofthe airflow Fm will be transformed into a static pressure. Accordingly,the blast pressure further rises through the fan guard, and the fan isthus supercharged.

Although such a near C configuration is exemplified as above to describea preferred embodiment, other configurations are acceptable as long asthe purpose of transforming a tangential velocity into a static pressurecan be achieved.

In another embodiment according to the present invention, the guardblades are arranged upstream of the rotor blades. As shown in FIG. 4,the position relationship between an upstream guard blade 403 and adownstream rotor blade 413 is illustrated at a moment that a leadingpoint C of the rotor blade 403 is moved to follow the camber line CL ofthe guard blade 403. The guard and rotor blades 403 and 413 at suchmoment constitute a near letter S configuration.

When the rotor device operates to have the rotor blade 413 revolve at atangential velocity Vr, the guard blade 403 guide air into the rotorblade 413 at an angle. Consequently, the air outflow from the guardblade 403 has an axial velocity Va and a tangential velocity Vt, andthus the airflow arriving at the rotor blade 413 has a tangentialvelocity of Vr+Vt. As known, the increase of the tangential velocityenhances the work of the rotor blades on air, so in this way, the fan issupercharged.

Although such a near S configuration is exemplified as above to describea preferred embodiment, other configurations are acceptable as long asthe purpose of providing an additional tangential velocity can beachieved.

Please now refer to FIGS. 5-8 which schematically show several compositefans which include a plurality of fan guards according to the presentinvention and/or rotor devices to further enhance fan efficiency.

The composite fan shown in FIGS. 5A and 5B is assembled by screwing theframes 511, 521 of the rotor devices 51, 52 and the frame 501 of the fanguard 50 together (FIG. 5A) so that the guard blades 503 can be upstreamof the rotor blades 523 and downstream of the rotor blades 513 (FIG. 5B)to simultaneously enhance the efficiencies of the upstream rotor device51 and downstream rotor device 523 so as to supercharge the compositefan.

FIG. 6 schematically shows another embodiment of composite fan accordingto the present invention. In this embodiment, there are a set of guardblades 603 located upstream of rotor blades 613 and another set of guardblades 623 located downstream of the rotor blades 613 to both enhancethe efficiency of the rotor device. By this way, the composite fan issupercharged.

A further embodiment of a composite fan is shown on FIG. 7 wherein twofan units, each consisting of a fan guard 70 according to the presentinvention and a rotor device 71, are directly coupled to form thecomposite fan.

On the basis of the above fan guard skeletons, at least one reinforcingring connecting the guard blades are preferably arranged forstrengthening the fan guard. Referring to FIG. 8, the fan guard 80includes two reinforcing rings 814.

Although the guard blades in the above embodiments are exemplified tohave a shape identical to the shape of the rotor blades, they can beplane plates or any other suitable shapes as long as the efficiency ofthe fan can be enhanced thereby.

The number of the guard blades need not be particularly limited, but oneto two times of the count of the rotor blades will result insatisfactory performance.

The guard blades can be made of plastic. Nevertheless, the guard bladescan also be made of a material other than plastic for a desired purpose.For example, when they are made of metal, the guard blades can serve asefficient heat-dissipating plates to further enhance theheat-dissipating efficiency.

To sum up, according to the present invention, the performance of a fancan be easily improved by changing the structure of the fan guardconventionally only used for supporting the fan. On the other hand, itis even advantageous because for the application to compact products,the high performance of the fan according to the present inventionallows the fan size to be reduced so as to be installed properly.

While the invention has been described in terms of what are presentlyconsidered to be the most practical and preferred embodiments, it is tobe understood that the invention need not be limited to the disclosedembodiment. On the contrary, it is intended to cover variousmodifications and similar arrangements included within the spirit andscope of the appended claims which are to be accorded with the broadestinterpretation so as to encompass all such modifications and similarstructures.

1. A fan guard to be mounted beside a rotor device of a heat-dissipationfan for supporting said rotor device and supercharging said fan,comprising: a main frame; a first set of guard blades radially arrangedinside said main frame and , fixed onto an inner surface of said mainframe by one ends end thereof, and respectively having a radially curvedprofile; a motor holder disposed inside said main frame for receivingand supporting a motor for driving the rotor device and enabling saidmotor to be received in a shaft ring of said rotor device; and a secondframe and a second set of guard blades arranged upstream of said rotorblades to guide air into said rotor device at an angle so as to make anair inflow to said rotor device have an additional tangential velocity,and thus enhance the work of said rotor blades on air; wherein saidfirst set of guard blades are arranged downstream of rotor blades ofsaid rotor device, and have a shape substantially identical to that ofsaid rotor blades, and an arrangement relative to said rotor bladesallowing any one of said guard blades and any one of said rotor bladesto constitute an approximate C configuration in a cross-sectional viewat a moment that a leading point of said guard blade aligned with atrailing point of said rotor blade in an axial direction, and whereincurves of said downstream guard blades guide an overall air outflow fromsaid rotor device to penetrate therethrough and be outputted in saidaxial direction, thereby transforming a tangential velocity of said airoutflow from said rotor device into a static pressure to superchargesaid fan.
 2. The fan guard according to claim 1 further comprising awherein said motor holder which is comprises a hollow cylindersubstantially located at the center of said main frame, and fixedthereto the other ends of said first set of guard blades for receivingtherein a motor used for driving said rotor blades to revolve.
 3. Thefan guard according to claim 1 further comprising at least onereinforcing ring connecting all of said guard blades for strengtheningsaid fan guard.
 4. The fan guard according to claim 1 wherein said guardblades are made of a material selected from a group consisting of aplastic and a metal.
 5. A fan guard for supporting a rotor device of aheat dissipation fan in order to supercharge said fan, comprising: anintegrally formed main frame for accommodating therein said rotordevice; a cylindrical motor holder disposed inside said main frame forreceiving and supporting a motor used for driving said rotor blades torevolve and enabling said motor to be received in a shaft ring of saidrotor device and positioned between the shaft ring and the motor holder;and a plurality of guard blades radially arranged inside said mainframe, fixed onto an inner surface of said main frame by each endthereof, and respectively having different crosssections; wherein saidguard blades have a shape substantially similar to that of rotor bladesof said rotor device, and said guard blades and said rotor blades arearranged in a specific configuration for allowing a tangential velocityof an airflow to be transformed into a static pressure so as tosupercharge said fan.
 6. The fan guard according to claim 5 wherein saidguard blades are arranged downstream of said rotor blades.
 7. The fanguard according to claim 6 further comprising another set of guardblades accommodated in said main frame and arranged upstream of saidrotor blades.
 8. The fan guard according to claim 5 wherein said guardblades are arranged upstream of said rotor blades.
 9. The fan guardaccording to claim 5 wherein a count of said guard blades is about 1˜2times of that of said rotor blades.
 10. The fan guard according to claim5 wherein said guard blades are made of plastic or metal.
 11. The fanguard according to claim 5 further comprising at least one reinforcingring connecting all of said guard blades for strengthening said fanguard.
 12. A heat dissipation fan comprising: a fan guard having a mainframe, and a plurality of guard blades radially arranged inside saidmain frame, fixed onto an inner surface of said main frame by each endthereof, and respectively having a curved profile with a cross-sectionalwidth that varies along a substantial portion of a chord of the guardblade; a rotor device mounted inside said main frame and having a shaftring and a plurality of rotor blades; a motor holder for receiving andsupporting a motor used for driving said rotor device to revolve andallowing said motor to be received in said shaft ring and positionedbetween the shaft ring and the motor holder; wherein said guard bladeshave a shape substantially similar to that of said rotor blades, and arearranged relative to said rotor blades for allowing a tangentialvelocity of an airflow to be transformed into a static pressure so as tosupercharge said fan.
 13. The heat dissipation fan according to claim 12wherein said motor holder is a hollow cylinder substantially located atthe center of said main frame, and effecting a junction with the otherends of said guard blades.
 14. The heat dissipation fan according toclaim 12 further comprising at least one reinforcing ring connecting allof said guard blades for strengthening said fan guard.
 15. The heatdissipation fan according to claim 12 wherein said guard blades arearranged upstream of said rotor blades of said rotor device.
 16. Theheat dissipation fan according to claim 12 wherein said guard blades arearranged downstream of said rotor blades of said rotor device.
 17. Acomposite heat-dissipating fan comprising: a fan guard having a mainframe and a plurality of guard blades radially arranged inside said mainframe, fixed onto an inner surface of said main frame by each endthereof, and respectively having a crosssection that varies along asubstantial portion of a chord of the guard blade; a first rotor devicehaving a frame and a plurality of rotor blades, wherein said guardblades are optionally arranged upstream or downstream of said rotorblades of said first rotor device; and a second rotor device arrangedupstream of said fan guard and said first rotor device which is arrangeddownstream of said fan guard, wherein said main frame of said fan guard,said frame of said first rotor device and a frame of said second rotordevice are assembled by screwing; wherein said guard blades have a shapesubstantially similar to that of rotor blades of said first rotordevice, and are arranged relative to said rotor blades of said firstrotor device for allowing a tangential velocity of an airflow to betransformed into a static pressure so as to supercharge said fan. 18.The composite heat-dissipating fan according to claim 17 wherein saidfan guard further comprises a motor holder which is a hollow cylindersubstantially located at the center of said main frame, and effecting ajunction with the other ends of said guard blades for receiving thereina motor used for driving said rotor blades to revolve.
 19. The compositeheat-dissipating fan according to claim 17 further comprising at leastone reinforcing ring connecting all of said guard blades forstrengthening said fan guard.
 20. The composite heat-dissipating fanaccording to claim 17 wherein said main frame of said fan guard and saidframe of said first rotor device are integrally formed together.
 21. Thecomposite heat-dissipating fan according to claim 17 wherein said guardblades are configured and arranged to simultaneously enhanceefficiencies of said first rotor device and said second rotor device.22. A fan guard for supporting a rotor device of a heat dissipation fanin order to supercharge said fan, comprising: a main frame; a pluralityof guard blades radially arranged inside said main frame; a holderlocated inside said main frame and integrally formed with said mainframe and said guard blades as a monolithic piece for receiving andsupporting a motor used for driving said rotor device to revolve;wherein said guard blades have a shape that is substantially similar tothat of rotor blades of said rotor device and that has a radially curvedprofile, and said guard blades and said rotor blades are arranged in aspecific configuration for allowing a tangential velocity of an airflowto be transformed into a static pressure so as to supercharge said fan.23. A heat dissipation fan comprising: a rotor device having a motor anda plurality of rotor blades; a fan guard having a frame surrounding saidrotor device and a motor holder receiving and supporting said motor; aset of guard blades radially disposed between said frame and said motorholder, respectively having a cross-section that varies along asubstantial portion of a chord of the guard blade, and integrally formedwith said motor holder and said frame of said fan guard together as amonolithic piece; said guard blades and said rotor blades having asubstantially similar shape relative to one another and being curved indifferent directions for allowing a tangential velocity of an airflowresulting from a revolution of said rotor blades to be transformed intoa static pressure so as to supercharge said fan.
 24. A compositeheat-dissipating fan comprising: a main frame; a first rotor devicedisposed in said main frame and having a shaft ring, a motor and aplurality of rotor blades arranged around said shaft ring; a fan guardhaving a frame, a motor holder for receiving and supporting said motorand enabling said motor to be received in said shaft ring of said firstrotor device and positioned between the shaft ring and the motor holder,and a plurality of guard blades radially disposed between said frame andsaid motor holder and respectively having a curved profile with across-section that varies along a substantial portion of a chord of theguard blade; wherein said guard blades and said rotor blades have asubstantially similar shape relative to one another and are relativelyarranged for allowing a tangential velocity of an airflow resulting froma revolution of said rotor blades to be transformed into a staticpressure so as to supercharge said fan.
 25. The compositeheat-dissipating fan of claim 24 wherein said guard blades are arrangedon an inlet side of said first rotor device.
 26. The compositeheat-dissipating fan of claim 24 wherein said guard blades are arrangedon an outlet side of said first rotor device.
 27. The compositeheat-dissipating fan of claim 24 wherein said motor holder is acup-shaped cylinder substantially located at the center of said frame ofsaid fan guard, and integrally formed with said guard blades and saidframe of said fan guard together.
 28. The composite heat-dissipating fanaccording to claim 24 further comprising at least one reinforcing ringconnecting all of said guard blades for strengthening said fan guard.29. The composite heat-dissipating fan according to claim 24 furthercomprising a second rotor device having a frame and a plurality of rotorblades.
 30. The composite heat-dissipating fan according to claim 29wherein said first rotor device, said second rotor device, and said fanguard are assembled in series.
 31. The composite heat-dissipating fanaccording to claim 29 wherein said first rotor device and said secondrotor device are disposed on two opposite sides of said fan guard. 32.The composite heat-dissipating fan according to claim 31 wherein saidmain frame of said first rotor device, said frame of said second rotordevice, and said frame of said fan guard are integrally formed together.33. A composite heat-dissipating fan comprising: a first fan unit havinga frame, a plurality of rotor blades, and a fan guard with a pluralityof guard blades respectively having a cross-section that varies along asubstantial portion of a chord of the blade and curved in a directiondifferent from that of said rotor blades of said first fan unit fortransforming an intake airflow into a static pressure to superchargesaid first fan unit; and a second fan unit having a frame, a pluralityof rotor blades, and a fan guard with a plurality of guard bladesrespectively having a cross-section that varies along a substantialportion of a chord of the blade and curved in a direction different fromthat of said rotor blades of said second fan unit for transforming anintake airflow into a static pressure to supercharge said second fanunit; wherein said first fan unit and said second fan unit are assembledtogether.
 34. The composite heat-dissipating fan according to claim 33wherein said first fan unit and said second fan unit are connected inseries.
 35. The composite heat-dissipating fan according to claim 33wherein said plurality of rotor blades and said plurality of guardblades of said first fan unit and said plurality of rotor blades andsaid plurality of guard blades of said second fan unit are alternatelyarranged in series.
 36. The composite heat-dissipating fan according toclaim 33 wherein said first fan unit and second fan unit are assembledby screwing.
 37. The composite heat-dissipating fan according to claim33 wherein said plurality of guard blades of said first fan unit andsaid plurality of guard blades of said second fan unit have inclinedangles, respectively.
 38. The composite heat-dissipating fan accordingto claim 33 wherein said first and second fan units further comprise atleast one reinforcing ring connecting all of said guard blades forstrengthening said fan guard thereof, respectively.
 39. A heatdissipation fan comprising: a rotor device having a motor and aplurality of rotor blades; a fan guard having a frame surrounding saidrotor device, a motor holder receiving and supporting said motor, and aplurality of guard blades radially disposed between said motor holderand said frame and respectively having a crosssection that varies alonga substantial portion of a chord of the guard blade; wherein said guardblades and said rotor blades have a substantially similar shape relativeto one another and are close to each other enough to allow a tangentialvelocity of an airflow resulting from a revolution of said rotor bladesto be transformed into a static pressure so as to supercharge said fan.40. The heat dissipation fan of claim 39 wherein said frame, said motorholder, and said guard blades of said fan guard are integrally formed asa single piece.
 41. The heat dissipation fan according to claim 39wherein said plurality of guard blades have inclined angles,respectively.
 42. The heat dissipation fan according to claim 39 furthercomprising at least one reinforcing ring connecting all of said guardblades for strengthening said fan guard thereof, respectively.